摄入不同量蛋白质对运动大鼠肝脏脂质过氧化作用的影响

采用Ｗｉｓｔｅｒ雄性大鼠，分组饲以７％、１７％、２７％蛋白质水平的饲料，观察运动对大鼠脂质过氧化作用的影响。结果表明：运动可改变肝脏脂质过氧化物的含量，运动后肝脏谷胱甘肽过氧化物酶活性增高，还原型谷胱甘肽含量下降，各组中以１７％蛋白质摄入水平大鼠运动耐力最强。据此可知，衰竭运动可增强脂质过氧化作用，运动对７％蛋白质摄入水平大鼠的影响最大，１７％蛋白质摄入水平可有效地抵御脂质过氧化作用，２７％组未显出这种优势。     

不同量和质的蛋白质对运动大鼠血糖,乳酸及耐力的影响

本文通过蛋白质７、１７、２７％（Ｗ／Ｗ）三种水平及不同质量组成的蛋白质喂养的三批大鼠游泳实验，以血乳酸、肌乳酸、血糖及肌糖原含量变化对大鼠运动耐力进行了观察。结果表明：在能量相等和平衡的情况下，饲料蛋白质含量以１７％水平为宜，其组成优质蛋白质占总蛋白量的４０％较好。     

不同质蛋白对运动大鼠蛋白质及能量代谢的影响

观察了三种不同质的动、植物蛋白质组成的含蛋白质１７％的饲料对运动大鼠蛋白质及能量代谢的影响。实验取雄性断轧幼鼠３２只，随机等分为Ａ、Ｂ、Ｃ、Ｄ四组。饲料中蛋白质组成：Ａ组为１００％麦蛋白；Ｂ组酪蛋白１０％，麦蛋白９０％；Ｃ及Ｄ组均为酪蛋白４０％，麦蛋白６０％。Ａ、Ｂ、Ｃ组为观察不同质蛋白质对运动大鼠蛋白质及能量代谢的影响，Ｄ组为Ｃ组的安静对照组。观察指杯有体重、氮平衡、骨骼肌氮、血清尿素氮、血糖、血乳酸、肌糖元、肌轧酸脱氢酶、肌ＡＴＰ和肌Ｃａ２＋－ＡＴＰ酶活性。结果表明：１．不同质蛋白影响大鼠蛋白质代谢。Ａ组蛋白质最差、运动后大鼠呈负氮平衡，且血清尿素氮含量较高，肌氮较低，表明蛋白质分解代谢增强。２．不同质蛋白也影响大鼠能量代谢，Ｃ组蛋白质较好，运动时消耗了较多的肌糖原，产生较多的ＡＴＰ；ＬＤＨ和Ｃａ２－ＡＴＰ酶活性较高。３．相同质蛋白的Ｃ、Ｄ组，运动的Ｃ组在能量的产生及酶活性等方面，其数值稍高于安静对照的Ｄ组。４．从蛋白质及能量代谢看，以酪蛋白与麦蛋白４：６为适宜。     

膳食锌和蛋白质的不同摄取水平对大鼠氮潴留影响的研究

将９６只刚断乳ＷＡＫ纯品系雄性大鼠随机分成４组，每组又分成４个亚组（６只／亚组），分别喂饲含５％、１０％、１５％、２０％蛋白质及２ｐｐｍ、６ｐｐｍ、１５ｐｐｍ、３０ｐｐｍ锌各指定饲料８周。在最后１周，测定食物、粪便、尿液中氮含量。结果尿氮随膳食蛋白质水平增加明显增加（Ｐ＜０．０５），粪氮损失随膳食锌摄入水平增加而明显降低，含锌２ｐｐｍ、６ｐｐｍ组表现氮潴留率明显低于１５ｐｐｍ、３０ｐｐｍ含锌组１１０％蛋白质水平和１５ｐｐｍ膳食锌时氮潴留率为最大。同时，蛋白质水平组≥１０％各组，尿氮、粪氮与血浆蛋白、血浆锌呈负相关（Ｐ＜０．０５）；而５％的蛋白质水平组，血浆蛋白、血浆锌只与尿氮有相关关系（Ｐ＜０．０１），而与粪氮无关（Ｐ＞０．０５）．说明本试验条件下：低蛋白膳食，锌对氮潴留影响意义不大，不是唯一的限定因素，只是一非控制因素；在适宜和较高水平的蛋白质摄入情况下，锌对氮潴留影响有重要意义，是一控制因素。     

膳食乳清蛋白和酪蛋白对大鼠肾钙质沉着作用的比较

本实验研究了不同水平的乳清蛋白和酪蛋白对雌性断乳大鼠肾钙质沉着（ＮＣ）作用的影响。饲料氮水平为２．４％（蛋白质１５％）时，乳清蛋白可显著降低大鼠ＮＣ的发生率。氮水平为４．８％（蛋白质３０％）时，酪蛋白也降低了大鼠ＮＣ的发生率，而乳清蛋白组大鼠未见到ＮＣ的发生。以１５％与酪蛋白和乳清蛋白组成相似的氨基酸混合物给大鼠，不影响ＮＣ的发生率；当氨基酸混合物增至３０％，可降低ＮＣ的发生率。结果提示：不同种类蛋白质影响大鼠肾钙质沉着与其氨基酸的组成无关，而可能与蛋白质的结构或某些非蛋白质组分有关。     

饲料蛋白质水平对大鼠蛋白质、锌、铁和铜吸收利用的影响

Ｗｉｓｔａｒ纯品系断奶雄性大鼠３２只，随机分成４组，喂纯合成饲料。第１、２、３、４组饲料含蛋白质分别为５％、１０％、２０％和１０％，其它成份相同，第５０天只有第４组改喂以无氮饲科并与其它三组同样收集５天粪、尿，测定氮及锌、铁、铜的代谢量，第５６天处死大鼠，测毛和肝、肾、脑、睾丸、胫骨中锌、铁、铜的含量。结果表明：低蛋白质水平组影响大鼠体重增长和蛋白质代谢，机体组织锌、铁，铜含量降低，经粪便排出锌、铁量增加，锌和铁的吸收与存留显著降低。本文还对蛋白质营养水平不同所致的锌、铁、铜营养状况缺乏时毛中锌、铁、铜含量作为诊断指标的意义进行了探讨。     

老年人需要哪些营养物质

老年人需要哪些营养物质文／马荫笃在日常生活中，食物中的三大主要成分为蛋白质、脂肪与碳水化合物。蛋白质对老年人最为重要。老年人应摄入充足的蛋白，假如每天摄入热量为８．４×１０３焦耳时，其热量１７％来自蛋白质、４７％来自碳水化合物、３６％来自脂肪，结果４...     

富含谷氨酰胺和支链氨基酸经肠营养制剂效用的研究

在国产１７种氨基酸（１７ＡＡ）注射液组成的基础上，将支链氨基酸（ＢＣＡＡ）从１０．４％提高到３０．０％，同时增加１２．０％的谷氨酰胺（ＧＬＮ），调整其余氨基酸的含量，组成Ⅰ和Ⅱ配方。２１只Ｗｉｓｔａｒ雄性大鼠随机分成对照组、Ⅰ和Ⅱ组，每组７只，行创伤手术后，分别饲以Ⅰ、Ⅱ和对照组配方为氮源的合成饲料，各组饲料等氮、等能量。实验期为１４ｄ，通过测定创伤后大鼠的体重恢复、伤口愈合状况、尾血淋巴细胞转化反应及小肠粘膜中核酸和蛋白质含量等指标，比较两种处方对创伤大鼠恢复的效果。结果表明：富含ＢＣＡＡ、ＧＬＮ的配方Ⅰ和Ⅱ对创伤大鼠营养支持效果截然不同，其中Ⅰ组动物体重增长、前白蛋白恢复、淋巴细胞转化反应、小肠粘膜核酸及蛋白质含量、伤口皮肤抗张力强度及胶原蛋白合成量等指标均明显不如Ⅱ组及对照组（Ｐ＜０．０５）；反之，Ⅱ组动物的小肠粘膜核酸及蛋白质含量显著高于对照组和Ⅰ组（Ｐ＜０．０５），伤口皮肤抗张力强度及胶原蛋白合成量亦显著高于对照组和Ⅰ组（Ｐ＜０．０５）。提示：研制复合氨基酸配方除需考虑一些氨基酸的药理学作用外，还必须照顾各氨基酸的合理比例。     

大鼠摄取不同饲料蛋白质水平对蛋白质和锌,铁,铜代谢的影响

Ｗｉｓｔａｒ纯品系断奶雄大鼠３２只，随机分成４组，喂纯合成饲料。第１、２、３、４组饲料含蛋白质分别为５％、１０％、２０％和１０％，其他成分相同，第５０天只有第４组改喂以无氮饲料并与其它３组同样收集５天粪、尿，测定氮及锌、铁、铜的代谢量，第５６天处死大鼠，测毛和肝、肾、脑、睾丸、胫骨中锌、铁、铜的含量。结果表明：低蛋白水平组影响大鼠体重增长和蛋白质代谢，机体组织锌、铁、铜含量降低，经粪尿排出锌、铁量增加，锌和铁的吸收与存留显著降低，本文还对蛋白质营养水平不同所致的锌、铁、铜营养状况缺乏时，毛中锌、铁、铜含量作为诊断指标的意义进行了探讨。     

不同质与量的蛋白质饲料对实验性营养不良大鼠体重及体组织成分恢复的影响——(二) 黄豆与牛肉蛋白质饲料

<正> 前文报导玉米和蛋清饲料,在自由摄食的情况下,对实验性营养不良大鼠的体重、肝重、肝氮量等的恢复速度有重大影响。本文比较了不同水平的优质植物性蛋白质——黄豆和动物性蛋白质——牛肉,在限制每日摄食量的条件下(摄入热量相等),对营养不良大鼠的恢复影响,进一步观察不同质与量蛋白质饲料的治疗效果。     

同位素~（65）Zn示踪法在研究膳食蛋白质与锌相互关系中的应用

本实验研究了不同来源膳食蛋白质及其摄取水平对大鼠锌吸收、分布、潴留、排泄及生物利用率的影响。结果表明：发芽大豆在各项指标上均优于普通大豆（Ｐ＜０．０１）；粪锌及粪￣（６５）Ｚｎ排出随膳食蛋白质水平的升高呈明显下降趋势，低蛋白组（５％）最高；表现￣（６５）Ｚｎ吸收率，表现Ｚｎ吸收率及表现Ｚｎ潴留率皆随膳食蛋白质水平增加而增加。５％蛋白质水平组明显低于蛋白质≥１０％各组（Ｐ＜０．０１），而１０％、１５％、２０％三组数值相接近，无显著性意义（Ｐ＞０．０５），提示低蛋白降低锌吸收与潴留，增加内源锌排泄；而１０％蛋白质，１５ｍｇ／ｋｇ锌为蛋白质和锌较适宜的膳食含量。在方法学上比较观察了￣（６５）Ｚｎ示踪法和总锌法。结果显示：大鼠肝、肾、胫骨、脑、睾丸各脏器Ｚｎ及￣（６５）Ｚｎ潴留存在明显正相关关系（Ｐ＜０．０５），且表现￣（６５）Ｚｎ吸收率与表现Ｚｎ吸收率、表现Ｚｎ潴留率呈高度正相关Ｐ（＜０．０５），示踪法特异性强，灵敏度高，无内源锌干扰，建议广泛使用，替代总锌法。     

Intravenously infused carnitine: influence on protein and branched-chain amino acid metabolism in starved and parenterally fed rats

We studied the effect of intravenously infused carnitine (34 mumol.100 g-1.d-1) on protein and branched-chain amino acid (BCAA) metabolism in rats either starved for 3 d or parenterally fed for 7 d. Carnitine infusion did not significantly affect nitrogen balance, protein content of liver and muscle, plasma concentrations of BCAA and branched-chain keto acid, or leucine oxidation and incorporation into liver and muscle proteins of either starved or fed rats. Despite a two- to threefold increase in plasma carnitine level, tissue concentrations of carnitine and its acyl-derivatives were not significantly affected by carnitine infusion. Of the amount of carnitine infused, 91% was lost in the urine of starved rats and 87% in the urine of fed rats. We conclude that intravenous carnitine infusion does not affect protein and BCAA metabolism and that this lack of effect may be related to the failure of carnitine infusion to enrich tissue pools of carnitine.     

Nutritional effects of field bean (Vicia faba L.) proteinase inhibitors fed to rats.

1. Weanling rats were fed on purified-casein diets containing active and inactive (autoclaved) field bean (Vicia faba L.) proteinase inhibitors (PI) at levels of 1.25, 2.5, 5.0 and 10 g/kg. Diets containing raw- and autoclaved-field-bean meal (FBM) were also given. The body-weight gain, protein efficiency ratio (PER); i.e. the ratio of the live weight gain in g/g of protein consumed and apparent nitrogen digestibility were determined 7, 14 and 21 d after the start of the trial. 2. Significant growth depression (P less than 0.001) was observed in rats given diets containing 2.5 g/kg PI (27--35%). In rats fed on raw FBM growth depression was severe after 7 d (57%). 3. Food intake was depressed at PI inclusion levels of 5 g/kg and higher between 14 and 21 d. 4. PER was depressed significanlty (33-44%) in rats given diets containing the active PI at all levels after 7 d. The protein utilization of all casein diets was higher than that of the FBM diets. 5. Apparent N digestibility was depressed in rats fed on diets containing 10 g/kg PI by 9 and 7% at 14 and 21 d respectively. The N digestibility of both raw and heated FBM was similar at approximately 84%. 6. It was concluded that the PI are not the main factors responsible for the growth depression observed when raw FBM is fed to rats.     

Garlic supplementation increases testicular testosterone and decreases plasma corticosterone in rats fed a high protein diet

The effects of garlic supplementation on protein metabolism were investigated by measuring testis testosterone and plasma corticosterone in rats fed diets with different protein levels. In Experiment 1, rats were fed experimental diets with different protein levels (40, 25 or 10 g/100 g casein) with or without 0.8 g/100 g garlic powder. After 28 d of feeding, testosterone contents in the testis were significantly higher and plasma corticosterone concentrations were significantly lower in rats fed 40 and 25% casein diets with garlic powder than in those fed the same diets without garlic powder. Urinary excretion of 17-ketosteroid (an index of testosterone), nitrogen balance and hepatic arginase activity were significantly higher in rats fed the 40% casein diet with garlic powder than in the 40% casein controls. In Experiment 2, the effect of diallyldisulfide (a major volatile sulfur-containing compound in garlic) on the secretion of luteinizing hormone (LH) from the pituitary gland, which regulates testosterone production in the testis, was investigated in anesthetized rats. Plasma LH concentration increased dose dependently after administration of diallyldisulfide (P < 0.01, r = 0.558). These results suggest that dietary supplementation with 0.8 g/100 g garlic alters hormones associated with protein anabolism by increasing testicular testosterone and decreasing plasma corticosterone in rats fed a high protein diet.     

Kinetic constants of lactase of the small intestine of growing rats fully recovered from protein depletion, in relation to dietary protein and lactose concentration

The effect of dietary composition on the kinetic constants of intestinal lactase was studied using rats depleted of protein by feeding protein-free diet from the weanling stage to 34 days of age and subsequently allowed to recover on diets containing 11.5 or 17% of protein calories (P%) and different levels of lactose (L%; 1, 15, 27 and 37%). After four days of refeeding, rats were decapitated and lactase activity was determined at different substrate concentrations by the method of Dahlqvist using homogenate of intestinal mucosa. Maximum velocity (Vmax) and Michaelis constant (Km) were calculated according to Eisenthal and Cornish-Bowden. At both levels of P%, Vmax tended to increase with the dietary lactose concentration. With diets containing 37% lactose, at P% 11 Vmax was about 60% of that at P% 17.0 Km tended to increase with L% in groups given the 17.0% protein calorie diets, but no difference was observed between groups fed at the lower level of protein. These results can be explained on the basis of interactions between dietary protein at different concentrations and inducer substrate which results in changes in isoenzyme patterns.     

Protein nutrition and aging.

Twenty-four female rats consisting of 6 sets of litters were used for the experiment. After weaning, rats were divided into 4 groups and fed with 10, 18, 27 and 36% casein diet. Effect of protein nutrition on aging was examined from the anthropometric and biochemical viewpoint. The difference of growth in body weight, and that of the urinary excretion of creatinine and 17-ketosteroids observed in the early period of growing disappeared by the end of growth period. From 1 year after birth, serum alkaline phosphatase activity and serum cholesterol were also measured. However, effect of protein nutrition on these parameters was not clear due to the scatter of data. The difference in diet did not affect life span in the present experiments, but the effect of the variance of litters on it seemed to be significant between the rats fed 18% casein diet and those fed 10% casein diet. Rats fed high-protein diet had a great number of lesions in the kidney and hypophysis, and often an incidence of tumors.     

Effect of dietary protein and methionine on sulfite oxidase activity in rats

Sulfite oxidase catalyzes the oxidation of sulfite to sulfate. To investigate whether or not sulfite oxidase activity (EC 1.8.3.1) is regulated by the amount of sulfur from dietary protein or excess methionine, we fed rats diets containing 5, 10, 20 and 50% casein with or without excess methionine and measured sulfite oxidase activity in liver and intestinal mucosa. Hepatic sulfite oxidase activity was significantly lower in rats fed 5 or 10% casein diets and significantly higher in rats fed 50% casein than in rats fed the control diet containing 20% casein, but activity did not change in response to the addition of methionine at any level of protein. Sulfite oxidase activity in the intestinal mucosa was only 5% of that seen in liver and did not change in response to dietary protein or methionine. Activity did not change in rats fed low iron diets (5 mg Fe/kg diet) at any level of protein tested or in response to glycine. These results show that sulfite oxidase activity can adapt to different levels of dietary protein but is unaffected by the level of methionine, total amino nitrogen or iron in the diet.     

蛋白质和食盐摄入量与血脂水平关系初探

本实验首先通过控制饲料蛋白质的供给量，观察不同蛋白质水平对小鼠嗜盐程度的影响，以探索蛋白质摄入量与嗜盐习性的关系。之后，进一步观察给盐的同时给予高胆固醇高脂肪饲料的小鼠血清总胆固醇（ＴＣ）和甘油三酯（ＴＧ）的水平变化，以探讨血脂代谢与蛋白质摄入量及嗜盐习性的关系。结果表明：低蛋白质（５．２％）饲料使小鼠自发饮用较多的盐水，有可能蛋白质供给量不足是嗜盐原因之一。小鼠摄食高胆固醇高脂肪饲料时，血脂水平明显升高（Ｐ＜０．０５）；同时饮用１．１％食盐水时，血清ＴＣ及ＴＧ水平更显著升高（Ｐ＜０．０１））．